2. INTRODUCTION; 2.1. HP-GL Syntax; 2.2. Font Selection- Page 355

CHAPTER 9 HP-GL - 4 

2.

INTRODUCTION 

The HP-GL graphics mode emulates 40 out of 56 instructions for the HP 7475A plotter made by Hewlett-
Packard. 

Default measurement unit in the HP-GL graphics mode is 1/1016"(0.025mm). 

2.1.

HP-GL Syntax 

A command consists of a two-letter instruction mnemonic, a parameter field (not needed for some instructions) 
and a terminator.  Parameters following the instruction mnemonic must be separated from each other by at least 
a single space or comma. 

P      A      10      20     ;

Instruction Mnemonic

Parameter Field

Terminator

At least one space or

comma (,) must be used

Numeric values used in the parameter field are in one of the following four formats. 

(1) Integer - integers between -2

30

 and 2

30 

-1.  Real numbers specified for a parameter that should be an integer 

are rounded to the nearest integer. 

(2) Clamped integers - integers between -32768 and 32767.  Values outside this range are converted to the 

nearest integer within the range.  Real numbers are rounded to the nearest integer. 

(3) Real - real numbers between -2

30

 and 2

30 

-1. 

(4) Clamped Real - real numbers between -32768 and 32767.  Values outside this range are converted to the 

nearest real number within the range. 

2.2.

Font Selection 

Eighteen character sets compatible with the HP 7454A are available. 

2.3.

Coordinate System and Printing Area 

2.3.1.

Coordinate system 

Paper feed direction

X

Y

Home Position

The home position is at the upper left corner of the area where printing is possible.